		/**
		 * ����չ��ܵ�ComboBox
		 **/
		Ext.form.ClearableComboBox = Ext.extend(Ext.form.ComboBox, {   
			initComponent: function(){   
				Ext.form.ClearableComboBox.superclass.initComponent.call(this);   
				this.addEvents('clear');   
		           
				this.triggerConfig = {   
				    tag:'span',   
				    cls:'x-form-twin-triggers',   
				    style:'padding-right:2px',   
				    cn:[   
					{tag: "img", src: Ext.BLANK_IMAGE_URL, cls: "x-form-trigger"},   
					{tag: "img", src: Ext.BLANK_IMAGE_URL, cls: "x-form-trigger x-form-clear-trigger"}   
				    ]   
				};   
			},   
		  
			getTrigger: function(index){   
				return this.triggers[index];   
			},   
		  
			initTrigger: function(){   
				var ts = this.trigger.select('.x-form-trigger', true);   
				this.wrap.setStyle('overflow', 'hidden');   
				var triggerField = this;   
				ts.each(function(t, all, index){   
				    t.hide = function(){   
					var w = triggerField.wrap.getWidth();   
					this.dom.style.display = 'none';   
					triggerField.el.setWidth(w-triggerField.trigger.getWidth());   
				    };   
				    t.show = function(){   
					var w = triggerField.wrap.getWidth();   
					this.dom.style.display = '';   
					triggerField.el.setWidth(w-triggerField.trigger.getWidth());   
				    };   
				    var triggerIndex = 'Trigger'+(index+1);   
			  
				    if(this['hide'+triggerIndex]){   
					t.dom.style.display = 'none';   
				    }   
				    t.on("click", this['on'+triggerIndex+'Click'], this, {preventDefault:true});   
				    t.addClassOnOver('x-form-trigger-over');   
				    t.addClassOnClick('x-form-trigger-click');   
				}, this);   
				this.triggers = ts.elements;   
			    },   
		  
			    onTrigger1Click: function() {this.onTriggerClick()},   
			    onTrigger2Click: function() {this.clearValue(); this.fireEvent('clear', this)}   
		});   
		  
		Ext.reg('clearcombo', Ext.form.ClearableComboBox); 
